Selective fuel tank content indicator



E. L. BEDARD SELECTIVE FUEL TANK CONTENT INDICATOR Filed July 30, 1945 flwezz/or ar/ Z gee 4rd Patented Aug. 2 2, 1944 SELECTIVE FUEL TANK CONTENT INDICATOR Earl L. Bedard, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application July 30, 1943, Serial No. 496,841

5 Claims. My present invention relates to a selective indicator for a plurality of tanks, such as the fuel tanks of an airplane engine or the like.

One object of the invention is' to provide' an indicator which normally indicates the content of a fuel tank from which fuel is being fed to the engine, the indicator being manually connectible with any of the other fuel tanks to determine their I contents, as desired, and upon release automatically returning to ind ate the tank from which fuel is being used.

A further object is to provide an indicator which will insure the pilot that none other than the tank lie is operating on will indicate on the instrument panel, except when he desires to determine the contents of any other selected one of his plurality of fuel tanks.

duit C respectively. The conduit 8 extends to any source of consumption such as the carburetor or fuel injector of an airplane engine, and the intake conduit C extends to the tank T The valve body I 0 has other intake conduits C2, C? and C connected to the respective fuel tanks T, T

and T The selector valve SV isstandard equipment on many airplanes and usually includes a control shaft 20 for the rotor l2 and a manually operable control handle 22. The control handle 22 has a pointer 24 cooperating with indicia such still a further object is to provide a single instrument panel indicator for the contents of several fuel tanks, so connected with a selector valve that normally only the tank from which fuel is being used through the selector valve will be indicated on the panel, as determined by the position of the selector valve.

Another object isto provide an electric indicating means for the contents of several fuel tanks wherein two selector switches are so interconnected with each other that one of them may automatically respond to the position of 'a selector valve and the other may be manually adjusted to determine the contents of any desired fuel tank other than the one being used from, the manual selector switch always returning to position for automatic indication again in response to the selector valve when the manual selector switchisreleased. w

With these and other objects in view, my inventionconsists in the construction, arrangement and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth,- pointed out in my claims, and illustrated in the accom panying drawing, wherein:

The figure is a diagram showing a plurality of fuel tanks and a selector valve to which my fuel tank content indicating means has been applied,

. the electric circuit of the indicating means being also shown diagrammatically.

1 On the accompanying reference characters T T, T and T to indicate four ta'nkssuch asthe fuel tanks of an airplane. A selector valve SV is shown having a housing i0 and a rotor l2. The rotor I! has a center port I4 and a side port ii for connection with a fuel supply conduit l8 and an intake condrawing, 1 have usedthe as 1, 2, 3, 4 and Off" on a'dial 26 mounted on the instrument panel, so that the pilot knows which fuel tank is in use at any time and the handle 22 permits him to change to any desired tank. In some instances, means is provided for automatically rotating the shaft 20 from one tank to the next when the fuel supply in the first tank fails.

My selective fuel tank content indicator includes a single gauge G for indicating the contents in any of the tanks T T, T or T For the purpose of actuating the gauge G, each tank is provided with a float F operating a potentiometer 28, and the potentlometers are connected in the circuit of the gauge G and a pair of selector switches. One of these selector'swltches may be termed a selector valve switch SS, and the other a manual selector switch MS. 5

The selector valve switch SS has a switch blade 30 and a plurality of contacts 32, 34, 36 and 38.

The manual selector switch has a switch blade 40 and a plurality of contacts 30a, 32a, 34a, 36a and 38a. The switch blade 30 is connected with the contact 30a and the four contacts of the switch SS are connected with the remaining four contacts of the switch MS, the contact 32 to the contact 32a, and so on.

A source of current supply such as a generator or a storage battery of an airplane is indicated at 42. One side of the battery is grounded at 44 and the other side is connected through a dropping resistor 46 to the gauge G and to one side of each potentiometer 28. The other side of each potentiometer 28 is grounded, as indicated at 48. The gauge G is also connected to the switch blade 40 and the contacts 32 to 38 are connected to the arms F F, F and F of the floats F in the repective tanks T T T and T The arms of th floats, it will be noted, variably contact with the resistance elements of the potentiometers and thereby the current flow in the coils of the gauge The manual selector switch MS may further include an operating shaft 50 for the switch blade $0, a control knob 52 and a dial 54. The switch blade 40 is normally held against a stop 56 which limits its position to engagement with the contact 30a as by a spring 58. By way of example, the spring 58 may be wrapped around the shaft and have its opposite ends engaging an edge of the bladell and a stationary pin 60. The dial 5 3 may be provided with indicia, such as Auto, 1, 2, 3 and 4, the four numbers indicating the four tanks T T, T and T respectively. 7

Practical operation Assuming that the selector valve SV is in position for supplying fuel from the tank T to the supply conduit 18, the selector valve switch blade 30 will be on the contact 92. Accordingly, current flow through the gauge G can be traced through the switch blade 40 of the switch MS, the contact 30a, the switch blade 30, and the contact 32, from which it flows to the float arm F Therefore'the float F in the tank T is the controlling factor for actuating the indicator or gauge G.

When it is desired to determine the contents in any of the other three tanks, the pointer of the knob 52 may be swung to the positions 2, 3 or 4 on the dial 54 and after the gauge reading is noted, the pointer may be swung to any of the other numbers, or the knob 52 released, whereupon the spring 58 will bring the switch blade 40 back to the contact 30a for connecting the circuit with the switch blade 30. Assuming for instance, that the contents of tank T is desired to be known, the pointer of the knob 52 may be registered with the indicia 3 on the dial 54 and the circuit from the gauge G then passes through the switch blade =10 and the contact 36a. From the contact 36a, the circuit may be traced upwardly to the float arm l so that the potentiometer 28 of the tank '1 is then the controlling factor, for the gauge G.

Whenever the knob 52 is released, it will automatically be returned by the spring 58 to the contact 30a, so that the position of the selector valve switch blade 30 is then the controlling factor for the gauge G, regardless of what position the blade 30 may be in. As a result, release of the manual selector switch MS always insures that the subsequent reading on the gauge G is for the tank from which fuel is being used, since the position of the selector valve determines the position of the switch blade 30 and thereby automatically, the proper potentiometer 28 for controlling the gauge G.

In this manner, it is impossible for the pilot to erroneously leave the manual selector switch MS on a tank from which fuel is not being used, thereby permitting him to use fuel from some other tank while the gauge remains at a position indicating fuel in such tank, not being used. Ii such were the case, fuel from the other tank may be completely depleted, thereby permitting the engine to stop while in flight.' This; of course, is a dangerous situation and'one that is guarded against bymy arrangement.

7 When the selector valve SV is adjusted to any position other than position 1 as shown, for instance position 3, the switch blade 30 will engage the contact 34 thereby automatically connecting the gauge G with the float arm F" to indicate the fuel level in the tank T" from which fuel is then being used. The circuit is then traceable from the gauge through the elements 40, 30, 34, F and. of T The knob 52 may now be registered with any 01 the indicia 1, 3 or 4 on the dial 54 for momentarily determining the contents of the tanks T 'I or T" and when the spring 58 returns it to position Auto," the gauge G willgive a reading for the tank 'I being used.

Basically, my arrangement makes it impossible for the gas gauge to indicate the contents of a tank to which the engines ar not connected, except when the pilot manually moves a switch to anyother tank position, such switch being biased to return to an automatic position positively indicating the tank from which fuel is actually being used.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms or structure or use of mechanical equivalents, which may be reasonably included within their scope without departing from the real spirit and purpose thereof.

I claim as my invention:

1. In combination with a plurality of fuel tanks and a selector valve for controlling fuel therefrom to a supply conduit, selective indicator means for the contents of said fuel tanks comprising a single indicating means for all of said tanks, switch means for selecting the tank effective to actuate said indicator means comprising a selector valve switch connected for simultaneous adjustment with said selector valve, a manual selector switch operable to connect said indicator means with any of said tanks desired independent of said selector valve switch, and means to normally return said manual selector switch to a position for permitting said selector valve switch to function.

2. In a selective tank content indicator, the combination with a plurality of tanks, and a selector valve between said tanks and a supply conduit, of content responsive means for each oi said tanks, an indicator adapted to be actuated by any one of said content responsive means, a manual selector means for selecting at will the content responsive means to actuate said indi- Gator, and an automatic means responsive to the position of said selector valve for automatically 7 selecting the content responsive means which actuates said indicator in accordance with the position of said selector valve, said manual selector means predominating said automatic means except when it is not being used to determine the contents of a tank other than the one cglnnected to said supply through said; selector v ve.

3. In combination with a plurality of tanks and a selector valve for controlling fluid therefrom to a supply conduit, selective indicator means for the contents of said tanks comprising an electrically energized content responsive means for each of said tanks, 9. single electrically actuated indicating means for said tanks, switch means for selecting the content responsive means eflective to actuate said indicator means comprising a selector valve switch normally connecting said indicator means w1th-the content responsive means of the tank from which fuel is being received through said selector valve, a manual selector switch operable to connect saidindicator means with the content responsive means of any of said tanks desired, independent of said selector valve switch, and means to return said manual selector switch to a position permitting said selector valve switch to function when the manual selector switch is released.

4. In combination with a plurality of liquid containing tanks and a selector means for controlling the flow bf liquid from said tanks to a common conduit, a liquid level indicator, liquid level responsive means for each of said tanks, and means for operatively connecting said liquid level responsive means with said indicator comprising a pair of selector devices, one automatically operable by said selector means as it changes position and the other manually operable, said manually operable selector device'having an initial position rendering said automatic selector device operable and other positions rendering it inoperative, said manually operable selector device selectively connecting said indicator with any one of said tanks.

5. In combination with a plurality of fuel tanks and a selector valve for controlling fuel therefrom to a supply conduit, selective indicator means for the contents of said tanks comprising an electrically energized content responsive means for each of said tanks, a single electrically actuated indicating means for said tanks, switch means for selecting the content responsive means efiective to actuate said indicator means comprising a multiple point selector valve switch, and a multiple point manual selector switch, said selector valve switch being operable to connect said indicator means with any of said tanks depending on the point of the switch in the indicator circuit, said manual selector switch being operable in normal position toconnectsaid selector valve switch in said circuit and in. other positions to disconnect it from said circuit, said manual selector switch, in said other positions, connecting various of said points of said selector valve switch in said circuit independent of said selector valve switch.

EARL L. BEDARD. I 

